The objective is to understand the vertebrate auditory system through a combined physiological and anatomical stud. A systematic description of stimulus coding in the ear and brain of lizards and cats will provide the foundation for interpreting physiological measures of human auditory activity. Some of the special techniques for studying electrical and mechanical responses in animals will be adapted for human work out of which may emerge new diagnostic methods. The basic work on stimuls coding forms a foundation for the development of prosthetic devices to bypass malfunctioning end organs. The many disciplines required for such a broad program make desirable a consortium of institutions incorporating experts in both scientific and clinical fields in a closely-kint joint venture.